serious, sometimes fatal events, such as infections, lymphoma, or other types of cancer, have happened. blood, liver and nervous system problems, serious allergic reactions, and new or worsening heart failure have occurred. before starting humira , your doctor should test you for tb. ask your doctor if you live in or have been to a region where certain fungal infections are common. tell your doctor if you have had tb, hepatitis b, are prone to infections, or have symptoms such as fever, fatigue, cough, or sores. you should not start humira if you have any kind of infection. ask your doctor if humira can work for you. this is humira at work. >>> welcome back to "squawk box" this morning. twitter's ipo expected to price in just about a day. and while there's a lot of excitement around the deal, there's also ha laundry list of potential risks raising eyebrows this morning. and kayla tausche joins us with more. some of those risk factors. >> it's tough to say, isn't it? the books for wall street close today around noon. and it's expected there's going to be high demand. they raised the pri